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gamma

1. the third letter in the Greek alphabet (Γ, γ), a consonant, transliterated as g. When double, it is transcribed and pronounced as ng
2. the third highest grade or mark, as in an examination
3. a unit of magnetic field strength equal to 10--5 oersted. 1 gamma is equivalent to 0.795 775 × 10--3 ampere per metre
4. Photog Television the numerical value of the slope of the characteristic curve of a photographic emulsion or television camera; a measure of the contrast reproduced in a photographic or television image
5. 
a. involving or relating to photons of very high energy
b. relating to one of two or more allotropes or crystal structures of a solid
c. relating to one of two or more isomeric forms of a chemical compound, esp one in which a group is attached to the carbon atom next but one to the atom to which the principal group is attached

gamma

(gam -ă) (γ) The third letter of the Greek alphabet, used in stellar nomenclature usually to designate the third-brightest star in a constellation or sometimes to indicate a star's position in a group.

Gamma

 

(1) A conventional unit that is sometimes used for measurements of small masses: 1 gamma = 10-6 g. The designation “microgram” (μg) is more frequently used than “gamma.”

(2) The name of a hundred-thousandth part of an oersted (the unit of magnetic field strength in the cgs system of units) that is used mainly for measurements of terrestrial magnetism and cosmic magnetic fields. It is designated by y.


Gamma

 

the quantitative characteristic of the ability of photographic material to transmit the difference in exposure H of various parts of a photographic image by the difference in the optical density D of the parts. The gamma is equal to the tangent of the angle of inclination to the axis log H of the straight portion of the performance curve of the material (provided that the scales of the axes log H and D are identical). Other conditions being equal, the gamma characterizes the uniformity of the silver halide crystals of the photographic emulsion with respect to light sensitivity. As a rule, it is greater for low-sensitivity positive materials and less for high-sensitivity negative materials. The gamma is one of the most important sensitometric parameters of a photographic material.

gamma

[′gam·ə]
(chemistry)
The gamma position (the third carbon atom in an aliphatic carbon chain) on a chemical compound.
(electromagnetism)
A unit of magnetic field strength, equal to 10 microoersteds, or 0.00001 oersted.
(graphic arts)
A numerical indication of the degree of contrast in a television or photographic image; equal to the slope of the straight-line portion of the H and D curve for the emulsion or screen.
(mechanics)
A unit of mass equal to 10-6 gram or 10-9 kilogram.

GAMMA

(language)
1. A language for matrices and generation of mathematical programming reports.

["GAMMA 3.3 for MPS/MPSX, IBM System:/360", Bonnor & Moore Assocs (Mar 1975)].

2. A high-level parallel language.

[Research Directions in High-Level Parallel Languages, LeMetayer ed, Springer 1992].

gamma

The way brightness is distributed across the intensity spectrum by a monitor, printer or scanner. Depending on the device, the gamma may have a significant effect on the way colors are perceived. Gamma is technically the relationship between the input voltage and resulting intensity of the output. A perfect linear device would have a gamma of 1.0 and be plotted on a graph called a "tone curve" as a straight line. Although a scanner is fairly linear, the tone curve of a monitor or printer is bent, yielding a gamma in the range of 1.8 to 2.6, which effects midrange tones. See gamma correction.
References in periodicals archive ?
In a commentary accompanying the NATURE article, Francis Halzen of the University of Wisconsin-Madison says that Markarian's gamma ray output suggests that the galaxy may emit an even higher intensity of elusive subatomic particles called neutrinos.
Cosmic-ray investigators caution that after nearly two decades of observations, they have pinpointed only a few possible sources of energetic gamma rays.
The Gamma Ray Observatory, launched April 6, may further spark interest in ground-based gamma-ray studies.
Like all space-borne technology, however, this observatory has limitations: It can study only "medium-energy" gamma rays - those with energies up to 10 billion electron-volts (10 GeV).
These scientists hope that the observatory's expected discovery of several hundred new medium-energy gamma ray sources may identify areas of the sky likely to emit higher-energy photons -- gamma rays whose presence can be inferred only from Earth.
Scientists once again turned skyward, searching for gamma rays.
But the variety of devices, each tailored to track the activity of gamma rays of different energy, share a common principle: They wait to see the light.
Together, the two detectors help distinguish signals produced by cosmic gamma rays from spurious light emitted by nearby sources.
Several other detectors at the Dugway site detect lower-energy gamma rays.
Though not energetic enough to make nitrogen glow, these gamma rays do induce a cylindrically shaped stream of charged secondary particles that induce a flash when they strike the plastic scintillators.
A relative paucity of muons indicates that a gamma ray likely induced the particle shower detected above ground; an abundance of muons suggests charged cosmic rays created the shower.
Surveying gamma rays at the same energies as the Chicago array, a set of 202 scintillators spreads over 85,000 square meters atop a plateau at Los Alamos National Laboratory.